fix: block POST requests to add comments (#1920)

Update the WAF ACL so that POST requests to add comments are
blocked.  This is being done because we are being spammed and
do not want to ever allow comments to be posted.

infrastructure/terragrunt/aws/load-balancer/waf.tf

@@ -625,6 +625,63 @@ resource "aws_wafv2_web_acl" "wordpress_waf" {
     }
   }
 
+  rule {
+    name     = "BlockComments"
+    priority = 13
+
+    action {
+      dynamic "block" {
+        for_each = var.enable_waf == true ? [""] : []
+        content {
+        }
+      }
+
+      dynamic "count" {
+        for_each = var.enable_waf == false ? [""] : []
+        content {
+        }
+      }
+    }
+
+    statement {
+      and_statement {
+        statement {
+          byte_match_statement {
+            positional_constraint = "CONTAINS"
+            search_string         = "wp-comments-post.php"
+            field_to_match {
+              uri_path {}
+            }
+            text_transformation {
+              priority = 0
+              type     = "LOWERCASE"
+            }
+          }
+        }
+
+        statement {
+          byte_match_statement {
+            positional_constraint = "EXACTLY"
+            search_string         = "post"
+            field_to_match {
+              method {}
+            }
+            text_transformation {
+              priority = 0
+              type     = "LOWERCASE"
+            }
+          }
+        }
+      }
+    }
+
+    visibility_config {
+      cloudwatch_metrics_enabled = true
+      metric_name                = "BlockComments"
+      sampled_requests_enabled   = true
+    }
+  }
+
   rule {
     name     = "WordpressRateLimit"
     priority = 101